Future evolution of surface temperature extremes and the potential impacts on the human health in Senegal

Abstract

Climate change impacts negatively vulnerable regions such as West African countries like Senegal, through an increase of climate extremes. The objectives of this study is to analyze the future evolution of the extreme temperature events and their impacts on human health in Senegal during the cold (DJF), hot (MAM) and wet seasons (JAS) under the greenhouse gas scenarios RCP4.5 and RCP8.5 using Climate projections of five (5) regional climate models (RCMs) of the Coordinated Regional Climate Downscaling Experiment (CORDEX) program. The results show that the biases of the RCMs are globally low especially their ensemble mean of the RCMs. This ensemble mean was afterwards considered in the analysis of the climate extremes in the near (2021-2050) and far future (2071-2100). When considering the near future, the frequency of the hot nights (Tn90p) increases under the scenario RCP8.5 (up to 90%) during the rainy season in the south of the country. As for the percentage of the hot days (Tx90p), it may reach approximately 70% under the scenario RCP8.5 in DJF over the majority of the country. Moreover, a strong increase of Tn90p and Tx90p is also diagnosed during the far future with values exceeding 80% over most parts of the country. Concerning the evolution of the heat wave magnitude index-daily, the ensemble mean of all models shows that the heat waves are more severe in MAM and JAS under both scenarios during the near and the far future over most parts of the country. To estimate the potential impacts of this heat stress on the human health, the heat index and the humidex are used. The analysis of the heat index shows that the sanitary risks are more perceptible over the whole country during the rainy season with values reaching the symptom band II for both scenarios during the far future. As for the humidex, it is characterized by a gradual increase from the historical period to the far future. This analysis highlights the fact that appropriate adaptation measures should be considered to tackle efficiently the increase of temperature extremes which may impact negatively the human health.

Potential Dust Induced Changes on the Seasonal Variability of Temperature Extremes Over the Sahel: A Regional Climate Modeling Study

“…The HI values obtained during the DJF period correspond to the symptom band I and that of the MAM, JJA, and SON seasons to the symptom band II ( Table 2). These results are in agreement with the findings of Meehl and Tebaldi (2004) and Sarr et al (2019). The difference between the two versions of the model shows that the accumulation of mineral dust in the atmosphere results in a decrease of the heat index especially in the northern Sahel during the MAM period, over the western Sahel during JJA, and over the central, the southern, and the northeastern parts of the Sahel during the SON period traducing a decrease of health risks.…”

“…During the wet season (JJA) and the SON period, the model simulates a north-south gradient with the lowest humidex located over the southern Sahel ( Figures 11C,D). The strongest values (>32°C) of this indice are recorded over the southern Sahel during the MAM period ( Figure 11B) and over the northern Sahel during the JJA and SON periods ( Figures 11C,D) in agreement with Sarr et al (2019) traducing evident discomfort (Category B and C in Table 3). The difference between both versions of the model shows that the dust impact is to decrease the humidex especially in the northwestern part of the Sahel during the DJF and MAM periods and over the central and the northeastern parts of the Sahel during the JJA and SON periods.…”

“…To go deeper in the characterization of dust impacts on heat indices related to human health, we analyzed the heat index (HI) and the humidex (HUM) which are the main standard indices used in numerous studies (Willett and Sherwood, 2012;Anderson et al 2013;Garland et al 2015;Sarr et al 2019). These healthrelated indices are generally based on meteorological variables which condition the temperature felt by humans.…”

“…This is the case of the Sahel whose economic development is based on rain-fed agriculture, therefore dependent on climatic hazards. Moreover, Ringard et al (2016) predict an intensification of temperature extremes over the Sahel and Guinea region during the future; this thermal extreme rise may impact negatively the human health (Sarr et al 2019).…”

Global and cross-country analysis of exposure of vulnerable populations to heatwaves from 1980 to 2018

“…For example, in reviews of case studies, by Campbell et al (2018) and Mora et al (2017), four studies were found for Africa and seven for South America. More recent works include studies for South Africa (Wright et al 2019) Senegal (Sarr et al 2019), and Brazil (Zhao et al 2018). The dataset developed by Guo et al (2018) included no data for Africa and limited data for Brazil, Chile, and Columbia.…”